I donât know what do you mean by pdf image, but if you want to simply convert pdf to an image you can easily do so. There are several applications to do that. For example, you can import the pdf page to Inkscape and then save the document as a png. There are other applications also, like libre office draw, etc. I think most of the drawing software can import pdf and then you can save as image. You can even take a screenshot of the page and save it.
In addition, use of different fonts on different platforms, maybe using different font that was recommended to the user, not sure about the specifics. When the document has some sections that are not visible, you would have to fix the problem. The PDF has only a single PDF file name that has to be shared, and the file extension needs to be .pdf, but you can use any extension you wish.